A CLOSER LOOK AT BACTERIA ALGAE AND PROrozo from bacteria and the Eukarya which con sists of all other organisms including plants and animals Scientists divide the bacteria into groups based on shape spherical cells which are labeled as cocci sing coccus rod shaped cells called bacilli bacillus curved rods known as vibrios and spiral shaped bacteria The latter group is further divided into spirilla Bacilli Klebsiella pneumoniae isolated from a lung abscess in a patient with pneumonia A W Rakosy EB Inc I2
THE DIVERSE WoRLD OF BACTERIA spirillum which are rigid thick spirals and spirochetes which are thin and flexible Virtually all bacteria have a cell wall sur rounding a cell membrane Within the cell membrane lies the cytoplasm a jellylike sub stance composedof water proteins and other molecules A single circular strand of DNA a complex molecule that carries all the infor mation about how a living thing will look and B who at a a S Cocci Staphylococcus aureus in a laboratory culture A W Rakosy EB Inc 13
A CLOSER LOOK AT BACTERIA ALGAE AND PROTOzou function floats freely in the cytoplasm So do ribosomes structures that help the bacteria make proteins Many species have indepen dent pieces of DNA called plasmids that can be transferred to other bacteria during repro duction In some species agelatinous capsule encloses the cell wall WHERE BACTERIA LIVE on 0 Bacteria are found in a great variety of habitats One teaspoon 5 millili ters of fertile soil may Contain as many as 500 million individual bac teria Some species live on and within other living things such as animals or fungi a rela tionship known as symbiosis Bacteria in habit oceans deserts hot springs and even snow The bacteria Neisseria flava from the human nasal passage A W Rakosy EB Inc 14
THE DIVERSE WORLD OF BACTERIA THIE FIRST LIFE FORMS The earliest simple life forms in the fossil record are prokaryotes namely bacteria and cyanobacteria formerly called blue green algae They have been found in rocks called stromatolites structures that are layered globular and often larger than a football A submersible passes over stromatolites in the Caribbean in 2006 The mounds are composed of sticky mats of cyanobacteria that cement sand and sediments Jonathan S Blair National Geographic Image Collection Getty Images
